Method of prevention of



Patented Oct. 16, 1951 METHOD OF-PREVEN1*I ON 0F DETERIORATION I-N srnnsMa'd'eline"G. Laiiibou, New 'Qrle'a 'orsto TheUnite'd'States or Am NoDrawing; ApplicationsNovjemherr8,:lil iih;

Serial N 0. 126,262?

5 Claims; (01. lst' ssl (Granted under the act ofsMa'rchi- 3; 1883,. assamended April 30, 1928;: 370:0. G -757)1 This application is made underthe-act OfJMM'Ch 3 1883,-as amended by. theiact. of April 30, 1928, andtheinvention herein described; if 5 patented,- ma'y be -manufactured andused bys'or for the Gov:

ernrnent of the United'States'of America for Overnm'en talpurposesiwithout: the payment to us' ofany. royaltyi'thereon.

This invention" relates l to seeds; particularlycottonseed, flaxseed,sunflower seed, rice, and grain sorghum, and-hagamong its objectstheapro- ViSiOl'l-iOf a=1 proce'ss of: chemicallytreajting such seeds toprevent their heating during storage. Another object is to allow for.drying of the seeds by aeration at atmospheric temperatures withoutsuffering any v lossin uality of the seed: An-

other object is to prevent the formation" of free.-

fatty acids-from glyceridesiin seeds: such as cottonseedJfiaxseedjrice,and so forth; during storage Other objects willa b'eapparent-iromthedefscription' of the inventiomfl The deterioration: ofseeds-"during? storage isthe result of-natural processesuinvolvingetheac.-

tivity *oi enzyme-systemswithin the seeds and :of micro-organismsassociated with the seedsw-When.

themoisture content ofseeds is high, various biological: processes areaccelerated and are refiected' in increased rates of deterioration.Moreover, whenseedof-high moisture contentisstored in bulk, the heatproduced by respiration and=es-' pecially by accelerated respirationcannot ordinarily be dissipated-rapidl from the-seed pilewiththe resultthatnthetemperature of the seed pi1e is increased The heating; of storedoilseeds,

grains, and other products of vegetableorigin by processes which aretheresult. of, .orwhich are i accompanied by, acceleratedtrespiration isommonlyireferred to as spontaneous heating, Spontaneous heating, orincreased'teinperatures resultingfrom biological activity of the seedand its associated micro-organisms, accelerates and aggravates various'deteriorative processes which normally take place to various degreesinseedof highrnoisture content.

Anyprocess which occurs during handling and storage of seed prior toprocessing and'which results in decreased value of the seed,"or of itsderived products, for food or industrial purposes may be classed asdeterioration. In oilsee'ds, such ascottonseed, fiaxseed' sunflowerseed, and so forth; the 'hydrolysis'of "the natural glycerides fats andoils) to form free fatty acids during storage constitutes an example ofa specific type of deterioration; Spontaneous heatingfofseeds instorageprovides ajiavorable environment for the growth of"niolds"andothenmicroo'rganis'm's' V i v 26 V which con-tr-ihutd to 'thetetalrespiration and -to' an augmentation of the heat evolved=- Anyan Iten sive mold proliferation or other microbi01og-i-'-- cal-activityirithe 'seed vl'r'hich results inlowering 1 the qii-dlity' and=utility= ofthe" seed on its derived p oudets' ror: food and industrialusesconstitutes ahother forn r" of deteiioratiens The development ofa-lenoriria l colors-=a nd flayors in stored seed like wiseconstitutesdeterioration?- Deterioration resulting from the activity andgrowth of molds and-fu'figi alsosrves toeattracta iid facilitate damageresorting from insect infestatieh Although the inetho ds and techniques!of central-oi insect infestation differ from those u'sed to corrtroldeterioration resulting from the biol'egi'c'al'activity 'of the seedsand-the resultirrg niiiero orgahisnisfl" the control of deteriorationcaused by the muse factors will-' indirectly he'lp infrri-inimizihdeterieration caused by insectse- A souridihealthy seed, deemsmamahdwithout anyserious bi'eakdwn o'f its cheinicarconstituents is loetteiable te w mandamusoverseas:-

Pri'r -to 'st'oi agee-it is' customary practice to reduce the-moisturecontent-of seed of excessively high rnei'sture by suclimethodsas-bloWing-warm' air o'vei' or throHgli -t e"-seed- This-isgenerallyaccomplished irP dryer which are mechanical de vices by meansofwhich vvarm air isblown' coun'- tercurrent*-to-"the= fio'v'v-="o'f theseedthus maki-ng possible the*redilutionof nioistu re' ina-con-tinr1'-"- ous manner? The ratej time; and 'costof "drying seed' bythis nieahs is' -dependent-'-upon the irritial moisture coii'tent'ofthe-seed. When seed is -har' vested by meaiis of ceinbii ies",' themoisture con bee'nshockedf an-djo'lried-'-'ir 1 the field pri or' tothreshing? This f'sedfmut" be 'd-ried immediately use harvest td preventexcessive"deterioration and ush -drying operations areinore *costlytharr d'ryingbi curing ln theshbfik. Oncesee'd-is dried tea -samenes*mem'oisture content;- it may be" storedin bulk"withoutseriousdeterioration for relativelylongfperiods; Frequently," however, a5,considerable""period of timeela'pses" beforethe about 30% moisture witha chemical mixture containing about ten parts, by weight, of propyleneglycol dipropionate to about one part, by weight, of1,3dimethyl-4,6-bischloromethylbenzene in a concentration of about from0.2 to 1.0% calculated on a dry weight basis of the seed, storing thetreated seed for a period of about from 1 to 3 days following thetreatment, and thereafter reducing and maintaining the moisture contentof the seed below about 15% by ventilating the seed without applicationof heat.

The delay of about 1 to 3 days is required in order to allow thechemical mixture to penetrate and distribute itself about the seed. Oncethis is accomplished, there will be no significant loss of chemical whenthe moisture is subsequently removed. It is desirable that the period ofstorage prior to removal of moisture be as short as possible. In thecase of seed containing approximately 20 to 30% moisture, one day isoften sufficient to allow for equilibrium to be reached between theseeds and the added chemicals.

The effect of this treatment is twofold. The activity of the enzymes ofthe seed which are responsible for heating and deterioration isinhibited. The other effect of our treatment is to eliminate or verygreatly reduce the ploliferation of molds and other micro-organisms inthe stored seed and thus obviate the harmful effects resulting fromtheir growth.

In most seed processing industries there is a preferred range ofmoisture content, generally below about 15%, which the seed should havein order to be processed properly in optimum yield of products of goodquality. In the case of rice, the preferred range is between 12 and 14%moisture content. A similar preferred range holds for the processing ofcottonseed. Seed of moisture content higher than the preferred content,even if it is sound and undeteriorated, must have some moisture removedprior to processing.

We have found that spontaneous processes leading to deterioration can beminimized and reduction in moisture to the range for optimum processingconditions accomplished by a combination of the aforementioned chemicaltreatment and aeration without application of heat.

The preferred treatment, according to the method of our invention, is tospray the seed. while it is being moved in a closed conveyor, with therequired amount of the chemical mixture. We have found that treatment ofthe seed with the chemical mixture in a concentration of about from 0.2%to 1.0% calculated on a dry weight basis of the seed, preferably in aconcentration of about 0.4%, will effectively inhibit deterioration forprolonged periods in all types of seeds having moisture contents up toabout 30%.

The seed is then stored in bulk in a bin or silo or any other convenientstorage facility. After storage for 1 to 3 days following treatment, theseed is aerated. This may be accomplished by drawing air through theseed pile by means of air-suction facilities placed under the seed pile.Another means of aeration is that of circulating the pile of seed over aconveyor system and returning it to the same or another bin in the seedhouse. Moisture will be removed from the seed by this process eitherwhen the relative humidity of the air surrounding the seed is less thanthe relative humidity of air in hygroscopic equilibrium with the seed orwhen the temperature of the surrounding air is approximately degrees F.lower than that of the seed. The

process of aeration may be repeated as often as convenient until themoisture content of the seed is reduced to a value considered optimumfor processing, generally below about 15%.

Several advantages are gained by drying seed by a combination ofchemical treatment and forced atmospheric-air ventilation. Drying can beaccomplished without use of expensive equipment. It can be accomplishedwith equal facility at processing mills and farms. Drying without use ofadded heat eliminates the danger of overheating the seed with itsattendant reduction in the quality of the seed products. Chemicaltreatment inhibits the respiration of the seed or of the micro-organismsassociated with the seed thereby preventing increase in the moisturecontent of the seed because water is one of the products of respiration.Chemical treatment therefore serves the purpose of stopping allbiological activity in the seed, including formation of moisture, untilthe moisture can be reduced by ventilation to a value at whichbiological activity and growth of micro-organisms is insignificant.Without the use of chemical treatment, ventilation by unheated air as ameans of drying seed is hardly feasible because the seed cannot be driedrapidly enough to prevent onset of rapid biological activity, moistureproduction, and deterioration.

The process of our invention is further illustrated, although it is notrestricted by the following examples:

Example I Flaxseed, having an initial free fatty acids content of 0.4%,was artificially conditioned to a moisture content of 20% and dividedinto two lots. One lot was treated with a mixture of chemicals containin10 parts, by weight, of propylene glycol dipropionate and one part, byweight, of 1,3-dimethyl-4,6-bischloromethylbenzene in a concentration of0.4 percent based on the dry weight of the seed and was then placed inan insulated container.

After two days storage, the chemically treated seed was removed from theinsulated container, exposed overnight to moderate air circulation in aforced-draft hood, and then returned to the insulated container.

The second lot of seed was not chemically treated. At the beginning ofthe storage experiment this lot of seed was exposed overnight tomoderate air circulation in a forced-draft hood and then placed in aninsulated container under conditions identical with those under whichthe treated seed was stored.

After 4 weeks of storage under the above-described conditions, sampleswere taken of the chemically treated and untreated lots of seed andanalyzed for moisture and free fatty acids content. The chemicallytreated seed had a moisture content of 12.5 percent and a free fattyacids content of 0.9 percent whereas the seed which had not beenchemically treated had a moisture content of 9.9 percent and a freefatty acids content of 5.5 percent.

Both lots of seed were aerated a, second time after approximately 5weeks of storage. After six weeks of storage a sample of the chemicallytreated seed had a moisture content of 5.4 percent and a free fattyacids content of 0.9 percent. The untreated seed had a moisture contentof 7.8 percent and a free fatty acids content of 16.4 percent. After 10weeks of storage th chemically treated seed had a free fatty acidscontent of 1.0 percent.

This experiment has demonstrated that drying by ventilation withunheated air is not sufiicient to prevent deterioration of the otherwiseuntreated fiaxseed. Chemical treatment followed with drying by means ofventilation with unheated air succeeded in completely preventingdeterioration of the seed.

Example II Fifteen tons of cottonseed of 18 percent moisture contentwere collected at a commercial oil mill and treated with a :1 mixture ofpropylene glycol dipropionate and1,3-dimethyl-4,6-bisch1oromethylbenzene at a rate of pounds of chemicalsper ton of seed. The treated seed was then placed in a bin forming a,seed pile 7-8 feet deep.

Thirty-six hours after treatment the treated seed was aerated for 69hours by blowing the air through the pile. Thirteen days after chemicaltreatment, the seed was again aerated for 24 hours. Crude oil producedfrom a sample of the original seed prior to chemical treatment andstorage had a refining loss of 11.5% and a Lovibond color of of yellowand 8.8 red. After days of storage under the above-described conditions,crude oil produced from the stored seed had a refining loss of 11.4% anda Lovibond color of 35 yellow and 9.3 red. The cottonseed had a finalmoisture content of 14.1 percent.

It is concluded from this demonstration that it is possible by means ofcombination of chemical treatment and aeration to dry cottonseed withoutapplication of heat and completely prevent de- 6 terioration for fortydays of storage, as measured by refining loss and color of the seedproducts at the end of the storage period.

We claim:

1. A process for preventing deterioration in quality of seed containingfrom 15 up to about 30% moisture resulting from biological activities ofthe seed and of the micro-organisms associated therewith comprisingtreating said seed with a mixture containing about 10 parts, by weight,of propylene glycol dipropionate to about one part, by weight, of1,3-dimethyl-4,6 bischloromethylbenzene in a concentration of 0.2 to1.0% calculated on a dry weight basis of the seed, storing said treatedseed for a period of from 1 to 3 days following the treatment, andthereafter reducing and maintaining the moisture content of the seedbelow about 15% by ventilating the seed without application of heat.

2. The process of claim 1 wherein the seed is an oilseed.

3. The process of claim 1 wherein the seed is cottonseed.

4. The process of claim 1 wherein the seed is flaxseed.

5. The process of rice.

claim 1 wherein the seed is AARON M. ALTSCHUL. MARJORIE Z. CONDON.MADELINE G. LAMBOU.

REFERENCES CITED Condon et al., Science, vol. 105, pp. 525-527 (1947).

1. A PROCESS FOR PREVENTING DETERIORATION IN QUALITY OF SEED CONTAININGFROM 15 UP TO ABOUT 30% MOISTURE RESULTING FROM BIOLOGICAL ACTIVITIES OFTHE SEED AND OF THE MICRO-ORGANISMS ASSOCIATED THEREWITH COMPRISINGTREATING SAID SEED WITH A MIXTURE CONTAINING ABOUT 10 PARTS, BY WEIGHT,OF PROPYLENE GLYCOL DIPROPIONATE TO ABOUT ONE PART, BY WEIGHT, OF1-3-DIMETHYL-4,6-BISCHLOROMETHYLBENZENE IN A CONCENTRATION OF 0.2 TO1.0% CALCULATED ON A DRY WEIGHT BASIS OF THE SEED, STORING SAID TREATEDSEED FOR A PERIOD OF FROM 1 TO 3 DAYS FOLLOWING THE TREATMENT, ANDTHEREAFTER REDUCING AND MAINTAINING THE MOISTURE CONTENT OF THE SEEDBELOW ABOUT 15% BY VENTILATING THE SEED WITHOUT APPLICATION OF HEAT.